This invention is directed to a brake adjusting tool and, in particular, to a brake adjusting tool for adjusting the automatic slack adjuster of an air brake.
Air brake systems for vehicles generally include a pneumatic actuator coupled by a crank to a shaft which moves a brake shoe against a brake drum of a wheel of the vehicle. The brake shoe is biased away from contact with the drum. When the brakes are applied, the pneumatic actuator moves a distance corresponding to the clearance between the shoe and the drum before braking begins. When the clearance is insufficiently close, dragging and overheating can occur in the brakes. When the clearance is excessive, an undesirable delay in brake application occurs and high pressure air is needed.
A slack adjuster is provided on each air brake for adjustment of the clearance between the shoe and the drum. The slack adjuster includes an adjustment bolt and, disposed about an exposed end of the bolt, a sealing plate. To properly adjust the clearance between the shoe and drum, the bolt must be turned and, occasionally, the sealing plate must be tightened down into the housing. While tightening the bolt will adjust the clearance, tightening the bolt without occasionally also tightening the sealing plate down about the bolt causes premature wear of gear teeth on the bolt and, therefore, premature failure of the slack adjuster. In particular, failure to tighten the sealing plate when tightening the adjustment bolt permits gear teeth on the bolt to only loosely mesh with a corresponding gear plate in the slack adjuster housing. This causes premature wear of the gear teeth. This problem is particularly important for fleet operators which are often forced to replace slack adjusters prematurely simply because the gear teeth of the adjustment teeth have worn.
The main reason for failure to tighten or loosen both the sealing plate and the adjustment bolt is lack of convenience. Tightening of both requires an assortment of wrenches. Further, the inconvenient positioning of the slack adjusters requires that when adjustment is required, a number of sockets must be carried under the vehicle. The slack adjuster on a semi-truck is located in a confined space of 4 to 5 inches and, therefore, only tools with a minimum size can be used. In particular, any useful tool can extend out from the slack adjuster no more than three inches and preferably no more than 2 inches.
In order to facilitate proper adjustment of air brake auto slack adjusters, a single tool is needed for adjusting both the sealing plate and the adjustment bolt of a slack adjuster.
A tool has been invented which is useful for adjusting both the sealing plate and the adjustment bolt of a slack adjuster. The adjustments can be made independently, as is required. The tool is of a small size to easily fit into the space about the slack adjuster.
In accordance with a broad aspect of the present invention, there is provided a tool for adjusting an automatic slack adjuster, the tool comprising: a body having an outer surface and a long axis extending between a first end and an opposite end, the first end including an annular face surrounding an opening, the annular face being coaxial with the long axis of the body and having a pair of diametrically opposed pins extending therefrom, the opposite end including an end face having formed therein a polygonal aperture, the polygonal aperture being positioned coaxially with the long axis of the body and the outer surface including a polygonal faceted region for engagement by a wrench, the polygonal faceted region being disposed about a centre axis positioned coaxially with the long axis of the body.
The tool is selected to adjust both the adjustment bolt and the sealing plate of a slack adjuster. In particular, the first end is formed to engage the sealing plate about the adjustment bolt of a slack adjuster while not engaging the adjustment bolt. The polygonal aperture at the opposite end is selected to engage the head of the slack adjuster adjustment bolt. The tool body can be rotated to transmit torque to either the adjustment bolt of the sealing plate by engaging the polygonal faceted region with a flat wrench.
The pins can be formed integral with the annular face or can be mounted on the annular face in a permanent or removable manner. In one embodiment, the pins are removably disposed in a pair of substantially parallel longitudinal bores formed diametrically opposed on the annular face. To permit for adjustment in the spacing of the pins, preferably a plurality of pairs of longitudinal bores are provided on the annular face for accepting the pins. Each of the pairs of longitudinal bores are diametrically opposed and each pair has a spacing therebetween different from each other pair.
In accordance with another broad aspect of the present invention, there is a method for adjusting an automatic slack adjuster including an adjustment bolt and a sealing plate disposed about the adjustment bolt, the method comprising: providing a tool including a body having an outer surface and a long axis extending between a first end and an opposite end, the first end including an annular face surrounding an opening, the annular face being coaxial with the long axis of the body and having a pair of diametrically opposed pins extending therefrom, the opposite end including an end face having formed therein a polygonal aperture, the polygonal aperture being selected to correspond to and engage the adjustment bolt""s exposed head and being positioned coaxially with the long axis of the body and the outer surface including a polygonal faceted region for engagement by a wrench, the polygonal faceted region being disposed about a centre axis positioned coaxially with the long axis of the body; fitting the polygonal aperture over the adjustment bolt""s exposed head; and rotating the tool to apply torque to the adjustment bolt.